Free Radical Polymerisation Process for Making Macromonomers

ABSTRACT

Process for preparing a macromonomer using free radical-initiated aqueous emulsion polymerisation in a polymerisation reactor of at least one olefinically unsaturated monomer, which process employs a hydrophobic Co chelate complex as a CTA, a stabilising substance(s) for the emulsion polymerisation process and a monomer feed stage MF; wherein an aqueous pre-emulsified mixture A, comprising at least part of the Co chelate(s) employed, at least part of the stabilising substance(s) employed, and (i) a non-polymerisable organic solvent(s) and/or (ii) a polymerisable monomer(s) in unpolymerised or at least partially polymerised form, is contacted in the reactor with monomer(s) of feed stage MF at the beginning of and/or during the course of feed stage MF; and wherein in mixture A the weight ratio of (i) and/or (ii) to the stabilising substance(s) is in the range of from 10/1 to 1/10.

The present invention relates to a process for the preparation of amacromonomer using a free radical-initiated aqueous emulsionpolymerisation of olefinically unsaturated monomer(s) in which ahydrophobic Co chelate catalyst(s) is used to control molecular weight.

Polymers of low molecular weight, known as oligomers, are often desiredfor various applications (such as coating compositions) either in theirown right or as precursors for other polymers. In order to formoligomers it is necessary to appropriately control the polymerisationprocess being used to yield the desired type of product. In free-radicalpolymerisations, which are widely used for polymerising olefinicallyunsaturated monomer(s) (which may for convenience be called “olefinicmonomer(s)”, “vinyl monomers” or “monomers” at various places in thisspecification), various conventional means are employed for controllingand limiting the molecular weight of the growing polymer chains. Ofthese, the addition of thiol compounds to the polymerisation hasprobably been used the most extensively; the thiol acts as an effectivechain transfer agent but unfortunately contaminates the system to whichit has been added by virtue of its distinctive and persistent odour.

More recently, attention has turned to the use of various transitionmetal complexes, particularly cobalt (Co) chelate complexes, as chaintransfer agents for use in controlling molecular weight when freeradically polymerising olefinic monomers.

For example, various literature references, such as N. S. Enikolopyan etal, J. Polym. Sci., Polym. Chem. Ed., Vol 19, 879 (1981), disclose theuse of cobalt II porphyrin complexes as chain transfer agents in freeradical polymerisation, while U.S. Pat. No. 4,526,945 discloses the useof dioxime complexes of cobalt II for such a purpose. Various otherpublications, e.g. U.S. Pat. No. 4,680,354, EP 0196783, EP 0755411, U.S.Pat. No. 4,694,059, and U.S. Pat. No. 5,962,609 describe the use ofcertain other types of cobalt II chelates as chain transfer agents forthe production of oligomers of olefinically unsaturated monomers byfree-radical polymerisation, the last mentioned of these concerning theuse of certain substituted benzildioxime complexes of Co II. WO 87/03605on the other hand claims the use of certain cobalt III chelate complexesfor such a purpose.

The use of such Co chelate complexes as chain transfer agents may inmany cases allow a considerably lower amount of chain transfer agent tobe used for molecular weight reduction than the use of other known andestablished chain transfer agents such as thiols for comparablemolecular weight reduction. Additionally, when polymerising certaintypes of monomer, these Co chelates allow the formation of a very highproportion of resulting oligomers having terminal unsaturation, known asmacromonomers, inherently produced as a result of the catalytic chaintransfer polymerisation (CCTP). (For ease of description, the entirepolymeric product resulting from such CCTP and containing a highproportion of oligomers with terminal unsaturation is termed herein amacromonomer, i.e. collectively including not only the high proportionof oligomers with terminal unsaturation but any oligomers not havingsuch terminal unsaturation). For example when an α-methyl vinylmonomer(s) is used as a monomer or comonomer in a (co)polymerisation ofolefinic monomer(s) , a terminally unsaturated low molecular weightmacromonomer in known to be formed. Well known examples of such α-methylvinyl monomers include methyl methacrylate, ethyl methacrylate, n-butylmethacrylate, hydroxyethyl methacrylate, methacrylamide,methacrylonitrile, and methacrylic acid, especially methyl methacrylateand/or ethyl methacrylate.

When conducting CCTP to form macromonomers one may use bulk, (organic)solution, aqueous suspension or aqueous emulsion polymerisation. Aqueousemulsion polymerisation is particularly beneficial, however, in that itgenerates polymer with a high level of macromonomer purity. In aqueousemulsion polymerisations as compared to polymerisations in organicsolvent systems, more chain events are necessary to achieve similarmolecular weight reduction. This results in the formation of a higherconcentration of chains ending with a double bond.

Depending on the nature of the ligands surrounding the cobalt, thechelate complexes can have very different solubility characteristics inwater. Thus some known Co chelate catalysts are hydrophilic, i.e. havesolubility not only in organic monomers and solvents but alsoappreciably in water, while others are hydrophobic, i.e. have solubilitysubstantially only in organic monomers and solvents and little or nosolubility in water and therefore being present in proximity to wherethe chain transfer events occur. Furthermore, hydrophobic Co chelatecatalysts may exhibit improved stability (see e.g. EP 755411).

When employing hydrophobic cobalt chelate complexes for CCTP in aqueousemulsion, it has been found that undesirably high amounts of the Cocatalyst are required in order to achieve a very much lowered molecularweight in the resulting macromonomer (although these are still muchlower in amount than hitherto used chain transfer agents such as thiolsfor comparable molecular weight reduction). This is particularly thecase where the emulsion polymerisation process involves feeding the Cocatalyst along with the monomer feed; such a process is currentlyfavoured in CCTP-based aqueous emulsion polymerisation since dissolutionof the Co catalyst in the monomer being fed allows accurate metering ofthe Co catalyst to be possible.

Such a disadvantage is not as marked when using hydrophilic Co chelatecatalysts, even though they might possibly be inherently less efficientthan some of the hydrophobic catalysts, and consequently this inventionis only directed to using hydrophobic Co chelate catalysts.

It will be appreciated that the presence of such relatively high levelsof Co catalyst is undesirable because of the typical colour they tend toimpart to the product, the health and environmental aspects of thepresence of heavy metals (in this case cobalt), and also the increasedprice of the products resulting from such higher levels of Co catalyst.

We have now invented a new process for CCTP in aqueous emulsion to forma macromonomer using a hydrophobic Co chelate catalyst, whereby such aprocess allows the preparation of very low molecular weight macromonomerusing a very significant reduction of the amount of Co catalyst hithertonecessary to achieve comparable molecular weight reduction when usingsuch a hydrophobic Co catalyst.

According to the present invention there is provided a process forpreparing a macromonomer using free radical-initiated aqueous emulsionpolymerisation in a polymerisation reactor of at least one olefinicallyunsaturated monomer, which process employs a hydrophobic Co chelatecatalyst(s) as a catalytic chain transfer agent(s) for controllingmolecular weight, a stabilising substance(s) for the emulsionpolymerisation process, and a monomer feed stage MF in whicholefinically unsaturated monomer(s) to be polymerised is fed to apolymerisation reaction medium in the reactor and polymerised therein;

and wherein an aqueous pre-emulsified mixture A, comprising at leastpart of the Co chelate(s) employed in the process, at least part of thestabilising substance(s) employed in the process, and (i) anon-polymerisable organic solvent(s) and/or (ii) a polymerisableolefinically unsaturated monomer(s) in unpolymerised or at leastpartially polymerised form, is contacted in the reactor with monomer(s)of feed stage MF at the beginning of and/or during the course of feedstage MF;

wherein in mixture A the weight ratio of (i) non-polymerisable organicsolvent(s) and/or (ii) polymerisable olefinically unsaturated monomer(s)in unpolymerised or at least partially polymerised form to stabilisingsubstance(s) is in the range of from 10/1 to 1/10.

It will be noted that there are two very closely related embodiments ofthe invention. In one, to be called herein embodiment G, pre-emulsifiedmixture A comprises a non-polymerisable organic solvent(s) (but nopolymerisable olefinic monomer(s) in unpolymerised or at least partiallypolymerised form) (employing alternative (i) in the above statement ofinvention). In the other (employing alternative (ii)) to be calledherein embodiment G′, pre-emulsified mixture A comprises a polymerisableolefinic monomer(s) in unpolymerised form or in at least partiallypolymerised form (but no non-polymerisable organic solvent(s)). Asindicated above by the use of “and/or” language, it is also possible touse a combination of embodiment G and embodiment G′ (i.e. employing bothalternatives (i) and (ii)). References or discussions relating tomixture A herein which do not mention embodiment G and/or embodiment G′are intended to be applicable to both embodiments or the combination ofthese embodiments.

In the process of the invention, an aqueous pre-emulsified mixture A asdefined above is contacted in the reactor with monomer(s) fed in feedstage MF at the beginning of and/or during the course of feed stage MF.It is preferable for all of the aqueous pre-emulsified mixture A to becontacted in the reactor with monomer(s) of feed stage MF at thebeginning of the feed stage (with contact being with the first part ofthe monomer(s) feed in feed stage MF, particularly if fed over aprolonged period), in which case mixture A can be made up in thepolymerisation reactor before the start of the feed stage MF, or can beprepared outside the reactor (e.g. in another vessel) and added to thereactor before the start of or contemporaneously with the start of feedstage MF. Mixture A could conceivably, in such case, be partially madeup inside and partially outside of the reactor.

Such a mixture A which is all contacted in the reactor with the monomerbeing fed in stage MF at the beginning of this feed stage couldadvantageously provide the, or a major part of the, initialpolymerisation reaction medium, provided other required components, suchas an initiator(s), are also present or are subsequently added thereto.

It is also optionally possible for all of the mixture A to be firstcontacted in the reactor with monomer(s) of feed stage MF during thecourse of this monomer(s) feed, i.e. after the commencement of the feedstage. In such case it would be necessary to prepare mixture A outsidethe reactor (e.g. in a separate vessel) and add it to the polymerisationmedium in the reactor at the desired time of first contact.

It is further possible for part of the mixture A to be contacted withthe monomer(s) of feed stage MF at the start of the feed stage and therest of mixture A to be contacted with monomer(s) of feed stage MFduring the course of the feed stage MF (it being understood that anypart of mixture A contacted during the course of the feed stage MF wouldhave to be prepared outside the reactor).

It will thus be appreciated that the pre-emulsified mixture A can becontacted in the reactor with monomer(s) of feed stage MF at anyconvenient point of the feed stage, but preferably when ≦50 weight % ofthe monomer(s) of feed stage MF has been fed to the reactor, morepreferably when ≦10 weight % of the monomer(s) has been fed, and mostpreferably (as discussed above) at the beginning of feed stage MF.

Additionally, if mixture A comprises a polymerisable olefinicallyunsaturated monomer(s) in at least partially polymerised form, andpreferably in substantially fully polymerised form, mixture A may bestored and used at a later time in the invention process, preferablybeing stored for at least 1 day, more preferably 3 days to 1 year,before subsequent use in the invention process.

In embodiment G of the invention process, the non-polymerisable organicsolvent(s) used for the pre-emulsified mixture A preferably dissolvesthe Co chelate(s) used in mixture A. Preferably, at least one of theorganic solvents (if more than one is used) is of very limited watersolubility, preferably having a water-solubility of ≦5 cm³/100 g ofwater, more preferably ≦2 cm³/100 g of water and most preferably ≦1cm³/100 g of water. Examples of non-polymerisable organic solvent(s)which could be used include, but are not limited to, aromatichydrocarbons such as benzene, toluene and the xylenes; linear alkanessuch as pentane, hexane, nonane and decane; linear alcohols such ashexanol, Texanol (Eastman Kodak), Lusolvan FBH (BASF), Coasol B(Chemoxy); and 2-ethylhexyl acetate. The organic solvent(s) mayoptionally contain other hydrophobic compounds provided that theviscosity of the mixture at the emulsification temperature is acceptablylow (preferably below 100 Pa.s).

In embodiment G′, the pre-emulsified mixture A comprises a polymerisableolefinic monomer(s) which can be in unpolymerised form before contact ofmixture A in the reactor with monomer(s) of feed stage MF, or can be inat least partially polymerised form, i.e. such monomer(s) in the lattercase being partly or substantially fully polymerised (the term“substantially” is used here because it is difficult to take anypolymerisation to absolutely 100% completion) before mixture A iscontacted in the reactor with monomer(s) of feed stage MF—and suchpolymerisation could e.g. be effected inside or outside of the reactoras desired or appropriate. It is preferred in the invention process touse embodiment G′ in which the polymerisable olefinic monomer(s) inmixture A is (are) in unpolymerised form before mixture A is contactedin the reactor with monomer(s) of feed stage MF (although of coursepolymerisation will certainly take place subsequently, along with themonomers of feed stage MF) rather than a non-polymerisable organicsolvent(s) (embodiment G), although the alternative of partly orsubstantially fully polymerised monomer(s) that can be used inembodiment G′ before contact of mixture A with monomer(s) of feed stageMF is equally if not more preferred, and compares favourably to the useof unpolymerised monomer(s) for the purposes of the invention and indeedmay possess an additional advantage in that the mixture could stand fora longer period (say several months) without the Co catalyst efficiencybecoming impaired.

The olefinic monomer(s) employed in mixture A of embodiment G′ (whetherin unpolymerised form or in at least partially polymerised form) is tobe considered as part of the olefinically unsaturated monomer(s) to bepolymerised in the invention process. Such a monomer(s) would normallybe the same as one or more or all of those that are fed in the feedstage MF, but could in principle be a different olefinically unsaturatedmonomer(s).

It will be appreciated that desirable solvent properties regardingpolymerisable monomer(s) used for mixture A in embodiment G′, whetherunpolymerised or at least partially polymerised before contact ofmixture A in the reactor with the monomer(s) of feed stage MF, willpreferably be the same or similar to those of the non-polymerisableorganic solvent(s) employed in mixture A for embodiment G. Thus in thealternative of embodiment G′ where the monomer(s) is unpolymerisedbefore contact with feed stage MF, the olefinic monomer(s) used formixture A preferably dissolves the Co chelate(s) present, so emulsifiedmonomer(s) containing dissolved Co catalyst(s) would be formed,stabilised with the stabilising substance(s). In the alternative ofembodiment G′ where the monomer(s) of mixture A is at least partiallypolymerised before contact with feed stage MF, the monomer(s) thereofagain preferably dissolves the Co chelate(s) before the at least partialpolymerisation takes place.

In view of this at least one of the monomers used in mixture A,embodiment G′ (if more than one is used), is preferably (as for thenon-polymerisable organic solvent(s) of embodiment G) of limited watersolubility and preferably the at least one monomer has awater-solubility of ≦5 cm³/100 g of water, more preferably ≦2 cm³/100 gof water, and most preferably ≦1 cm³/100 g of water. As mentioned above,the monomer(s) used is preferably the same as one or more of those usedin feed stage MF. Suitably monomer(s) used in embodiment G′ of mixture Apreferably include one or more of methyl methacrylate, ethylmethacrylate, and n-butyl methacrylate, more preferably methylmethacrylate and/or ethyl methacrylate. The monomer(s) may optionallycontain other hydrophobic compounds provided that the viscosity of themixture at the emulsification temperature is acceptably low (preferablybelow 100 Pa.s).

As mentioned above, it is also within the scope of the invention toemploy a combination of embodiments G and G′ in the process of theinvention, so that mixture A (before contact with the monomer(s) of feedstage MF) contains a non-polymerisable organic liquid and either anunpolymerised monomer(s) or an at least partially polymerisedmonomer(s).

In embodiments G and/or G′ the Co chelate catalyst(s) in mixture Abecomes (it is thought) finely dispersed, whether present dissolved inemulsified non-polymerisable organic solvent (as in embodiment G it isthought) or dissolved in emulsified monomer droplets (as in the firstmentioned option of embodiment G′ it is thought) or adsorbed inpolymerised polymer particles (as in the second mentioned option ofembodiment G′ it is thought). In any case, once monomer feed stage MF isunderway, and polymerisation of the monomer(s) fed via feed stage MF inthe reactor has commenced, the status of the monomer(s)/Co catalyst(s)of mixture A in both alternatives of embodiment of G′ will (it isthought) tend to become essentially the same.

The effectiveness (i.e. efficiency) of a hydrophobic Co chelate catalystwhen used as part of a pre-emulsified mixture A in the invention processhas been found to be generally 5 to 30 times greater than that of thesame amount of the same Co chelate present only in, or separately fedwith, the monomer(s) to be polymerised in feed stage MF.

The components of aqueous pre-emulsified mixture A comprising Co chelatecatalyst(s), (i) non-polymerisable organic solvent(s) and/or (ii)polymerisable monomer(s) in unpolymerised or at least partiallypolymerised form, and stabilising substance(s) may be brought togetherin any order, using any appropriate agitation means to effectemulsification in water of the nonaqueous components, such as aneffective stirrer or homogenisation equipment. The agitation foremulsification is usually effected at ambient temperatures (ambient orroom temperature is taken herein as 10 to 40° C.) althoughemulsification at higher temperatures is possible.

The prefix “pre” in “pre-emulsified mixture” is used to emphasise thatsuch mixture is separately formed from the monomer(s) fed in feed stageMF and normally formed before the start of the MF feed stage.

By the term “emulsified” in “pre-emulsified mixture” is meant that thereare dispersed in water colloidally sized droplets of non-polymerisableorganic solvent(s) and/or unpolymerised monomer(s) containing dissolvedCo catalyst(s) or, in the case where monomer(s) which has dissolved theCo catalyst has been at least partially polymerised before contact inthe reactor with monomer(s) of feed stage MF, colloidally sizedparticles of polymer containing Co catalyst(s) disposed therein,together with any intermediate states arising from partially polymerisedmonomer(s), the droplets and/or particles (and/or any intermediatestates if monomer(s) used is partially polymerised before contact in thereactor with monomer(s) of feed stage MF) being stabilised with thestabilising substance(s).

As mentioned above, this invention is not intended to cover usinghydrophilic Co chelate catalysts where the advantage of using theinvention process is much less apparent.

There is further provided according to the invention a macromonomerwhich has been formed using a process as defined above. Such amacromonomer may contain a very small amount of hydrophobic Co chelatecatalyst(s) because such a catalyst(s) can be used in significantlyreduced quantity in the invention process than hitherto necessary toachieve comparable very low molecular weight. Preferably, the processaccording to the invention uses, and the macromonomer resultingtherefrom contains, essentially ≦100 weight parts per million (ppm) ofthe Co chelate catalyst(s) based on the total weight of monomer(s) usedfor the polymerisation (including any used in mixture A as well as infeed stage MF), preferably ≦60 weight ppm, more preferably ≦35 weightppm, and most preferably ≦20 weight ppm.

The process of the invention involves the use of aqueous emulsionpolymerisation to form colloidal-sized macromonomer particles dispersedin water. The use of aqueous suspension polymerisation, thereby to formgranules or beads, is excluded, as is aqueous microsuspensionpolymerisation (also known as mini-emulsion polymerisation) wheremicrodroplets of monomer are formed using homogenising apparatus orselected cosurfactants and then polymerised, since in this latter casealthough an aqueous emulsion of colloidal-sized polymer particles canresult, there are no new particles formed in the polymerisation processwhereas in the present invention secondary nucleation to form newparticles has been observed to occur during the polymerisation (a knowncharacteristic of aqueous emulsion polymerisation but notmicrosuspension polymerisation).

The aqueous emulsion polymerisation of the invention process preferablyresults in a macromonomer aqueous emulsion of particle size, as measuredwith light scattering equipment, within the range of from 10 to 300 nm,more preferably from 15 to 200 nm, and particularly from 20 to 150 nm.The solids content of the resulting macromonomer aqueous emulsion isusually within the range of from 10 to 50 weight % and more preferablyfrom 20 to 45 weight %.

The aqueous emulsion of macromonomer resulting from the inventionprocess may be stored or used as such (with optional dilution with wateror optional concentration), or (less preferably) the macromonomer mayfirst be isolated before subsequent use or before storing.

The amount of Co catalyst employed in mixture A is preferably 10 to 100weight % based on the total weight of Co catalyst employed in theinvention process, more preferably 50 to 100 weight % (and bearing inmind that the preferred total absolute amount of Co chelate catalystused is, as mentioned above, essentially ≦100 weight ppm based on totalweight of monomer(s) used for the polymerisation, more preferably ≦60weight ppm, more preferably ≦35 weight ppm and most preferably ≦20weight ppm).

The remaining Co catalyst, if any (since all may, if desired, be used inthe mixture A), is added separate to and usually after the introductionof mixture A to the reactor.

The maximum amount of Co catalyst in the mixture A when (co)polymerisingan α-methyl vinyl monomer(s) of formula II (see later for this formula)is preferably governed by the following empirical relationship:Mw [Co-complex]/m^(1/2)≦0.35 Dalton   IwhereMw is the achieved weight average molecular weight of the macromonomerin Dalton;[Co-complex] is the concentration Co chelate catalyst(s) in mixture A inmol ppm based on total monomer(s) used in the invention process; andm is the average number of carbon atoms of the alkyl, aryl or aralkylsubstituent(s) of the α-methyl vinyl monomer(s) (or the weight averagenumber of the number of carbon atoms of such substituents if using morethan one α-methyl vinyl monomer).

Molecular weights of oligomers, macromonomers and polymers as specifiedherein are those determined using gel permeation chromatography (GPC)relative to polymers of known molecular weight. GPC is calibratedaccording to polystyrene standards.

The amount of (i) non-polymerisable organic solvent(s) and/or (ii)polymerisable olefinic monomer(s) used for mixture A (whether inunpolymerised form or in at least partially polymerised form in the caseof embodiment G′), is preferably within the range of from 1 to 20 weight% based on total amount of monomer(s) used for the polymerisation, morepreferably from 2 to 10 weight % and particularly from 2.5 to 7.5 weight%. Thus it will be noted that the (i) non-polymerisable organicsolvent(s) and/or (ii) polymerisable monomer(s) in unpolymerised or atleast partially polymerised form used for mixture A is preferably only asmall fraction of the total monomer(s) employed for the inventionpolymerisation process (i.e. including that of feed stage MF as well asthat for mixture A in embodiment G′).

The weight ratio of (i) non-polymerisable organic solvent(s) and/or (ii)polymerisable monomer(s) (whether in unpolymerised or at least partiallypolymerised form in embodiment G′) to stabilising substance(s) inmixture A is preferably in the range of from 5/1 to 1/5 (weight/weight)and particularly from 3/1 to 1/3 (weight/weight). It will be noted thatthe preferred concentration of stabilising substance(s) in mixture A isvery high with amounts of 25 to 75 weight % or more based on (i)non-polymerisable organic solvent(s) and/or (ii) polymerisablemonomer(s) (whether in unpolymerised or at least partially polymerisedform) present as the case may be not being unusual.

The stabilising substance(s) employed in mixture A may be asurfactant(s) or a hydrophilic oligomer(s). Combinations of these mayalso be used.

A wide range of surfactants may be used such as those commonly employedin aqueous emulsion polymerisation of olefinically unsaturated monomers.They may be of the ionic type, including anionic or cationic, or of thenonionic type. Combinations of ionic and nonionic surfactants may alsobe used, especially combinations of anionic and nonionic surfactants.

Suitable surfactants include but are not limited to conventionalanionic, cationic and/or nonionic surfactants and mixtures thereof, suchas Na, K and NH₄ salts of dialkylsulphosuccinates, Na, K and NH₄ saltsof sulphated fatty acids or fatty alcohols, Na, K and NH₄ salts of alkylsulphonic acids, Na, K and NH₄ alkyl sulphates, alkali metal salts ofsulphonic acids; fatty alcohols, ethoxylated fatty acids and/or fattyamides, and Na, K and NH₄ salts of fatty acids such as Na stearate andNa oleate. Other anionic surfactants include alkyl or (alk)aryl groupslinked to sulphonic acid groups, sulphuric acid half ester groups(linked in turn to polyglycol ether groups), phosphonic acid groups,phosphoric acid analogues and phosphates or carboxylic acid groups.Cationic surfactants include alkyl or alkaryl groups linked to permanentquaternary ammonium salt groups or protonated tertiary amino groups.Nonionic surfactants include polyglycolether compounds and preferablypolyethylene oxide compounds as disclosed in “Non-IonicSurfactants—Physical Chemistry” edited by M. J. Schick, M. Decker 1987.

The amount of surfactant(s) if used in mixture A is preferably withinthe range of from 0.1 to 5 weight % based on total monomer(s) used inthe invention polymerisation process, more preferably from 0.5 to 5weight % and particularly from 1 to 3 weight %. Additional surfactant(s)to that in the mixture A could also if desired be employed during thepolymerisation reaction of the monomer(s) of monomer feed stage MF (notnecessarily but usually the same as that used in mixture A ), e.g. byfeeding during the MF feed, in order to further stabilise themacromonomer particles being formed.

By hydrophilic oligomers is meant herein oligomers (i.e. low molecularweight polymers) which possess the property of self-dispersibility inwater (i.e. dispersible in water without the need to use externalsurfactant(s)), preferably being self-dispersing acrylic or urethaneoligomers or combinations of the two. They are usually self-dispersingoligomers of olefinic monomers, particularly acrylic oligomers orpolyurethane oligomers, but can also be self-dispersing oligomers of anysuitable type, e.g. self-dispersing polyester polymers. This property ofself-dispersibility is achieved by the presence of self-dispersinggroups in the oligomer, which can be introduced directly into theoligomer during the polymerisation to form it by including monomer(s)carrying such groups, or functional groups may first be introduced intothe oligomer which can be subsequently reacted to form a self-dispersinggroups. Some dispersing groups, such as carboxylic acid groups (e.g.from (meth)acrylic acid often used as water-dispersing monomer) canperform more than one function, e.g. (meth)acrylic acid is often used asa water-dispersing monomer, but can also act as a crosslinking monomerif suitable conditions are present (such as the presence of co-reactivecrosslinking groups in the system for example from an added crosslinkingagent or the presence of co-reactive groups in the oligomer, or both).Ionic water-dispersing groups may need to be at least partly in theirdissociated form to effect their water-dispersing action; e.g. acidgroups such as carboxylic acid may need to be treated with a base suchas ammonia, or volatile organic amine, or Na, Li, or K hydroxide if ofinsufficiently low pK to be dissociated in water. If they are notdissociated they are considered as potential ionic groups which becomeionic upon dissociation. The ionic water-dispersing groups arepreferably fully or partially in the form of a salt when used in theinvention. Ionic and potentially ionic water-dispersing groups includecationic water-dispersing groups such as basic amine groups, quaternaryammonium groups and anionic water-dispersing groups such as acid groups,for example phosphoric acid groups, sulphonic acid groups and (mostpreferably) carboxylic acid groups.

Preferred olefinically unsaturated monomers providing anionic orpotentially anionic water-dispersing groups include (meth)acrylic acid,itaconic acid, maleic acid, β-carboxyethyl acrylate, monoalkyl maleates(for example monomethyl maleate and monoethyl maleate) and citraconicacid. Acrylic acid and methacrylic acid are particularly preferred. Ifthe macromonomer to be formed in the invention process is to bearcarboxylic acid groups derived from unsaturated acids such as acrylicacid or methacrylic acid, it may be necessary that any unsaturated acidsused in the formation of a hydrophilic oligomer has a pKa value belowthat of acrylic acid or methacrylic acid, for example phosphatedhydroxyethyl methacrylate, sulphonated styrene, sulphated hydroxylethylmethacrylate and salts thereof, 2-acrylamido-3-methylpropane sulphonicacid (AMPS) (Lubrizol), Sipomer PAM-100 and Sipomer PAM-200 (Rhodia)(thereby reducing the likelihood of an acid functional hydrophilicoligomer used as stabilising substance in the invention process itselfbecoming destabilised).

A preferred monomer for providing self-dispersing groups in polyurethanepolymers is dimethyl propionic acid (DMPA). Others which may be usedinclude sodio-5-sulpho isophthalic acid (SSIPA) and diethyleneglycolSSIPA (Eastman Chemicals).

Non-ionic water-dispersing groups may be in-chain, pendant or terminalgroups. Preferably non-ionic water-dispersing groups are pendantpolyoxyalkylene groups, more preferably polyoxyethylene groups.Preferred ethylenically unsaturated monomers providing non-ionicwater-dispersing groups include alkoxy polyethylene glycol(meth)acrylates, hydroxy polyethylene glycol (meth)acrylates, alkoxypolypropylene glycol (meth)acrylates and hydroxy polypropylene glycol(meth)acrylates, preferably having a number average molecular weight offrom 350 to 3000. Examples of such monomers which are commerciallyavailable include (o-methoxypolyethyleneglycol (meth)acrylate. Otherolefinically unsaturated monomers providing water-dispersing groupsinclude (meth)acrylamide, hydroxyalkyl (meth)acrylates such ashydroxyethyl methacrylate, acetoacetoxylethyl methacrylate,diacetonacrylamide and acetoacetoxy methacrylamide.

Preferably acid monomers are employed for providing self-dispersibilityin such hydrophilic oligomers, typically methacrylic acid or acrylicacid, in the cases of olefinic oligomers (i.e. oligomers formed bypolymerisation of olefinically unsaturated monomers) and DMPA in thecase of urethane polymers. Preferably, in such cases, the acidconcentration of the oligomer is provided by 2 to 40 weight % of acidmonomer(s) based on total monomer(s) to make the oligomer (more than oneacid monomer could of course be used), more preferably 2 to 25 weight %and particularly 4 to 12 weight %. Other non-acid hydrophilic monomers,such as those mentioned above could also be used with the acidmonomer(s) to form the oligomer, such as diacetoneacrylamide,methacrylamide or polyethylene glycol (PEG) functional monomers. Thesame preferred ranges as used above for acid monomer(s) would also beapplicable for non-acid hydrophilic monomer(s) if used (weight % basedon total monomer(s) used to make the oligomer).

The weight average molecular weight of the hydrophilic oligomer (ifused) is preferably in the range of from 1 to 200 kD (D=Dalton), morepreferably 2 to 130 kD, more preferably 2 to 60 kD and particularly 5 to25 kD. Lowering of molecular weight to achieve an oligomer could beeffected by employing a chain transfer agent in the polymerisationreaction. Examples include mercaptans and halogenated hydrocarbons, forexample mercaptans such as n-dodecylmercaptan, n-octylmercaptan,t-dodecylmercaptan, mercaptonethanol, iso-octyl thioglycolate, C₂ to C₈mercapto carboxylic acids and esters thereof such as 3-mercaptopropionicacid and 2-mercaptopropionic acid; and halogenated hydrocarbons such ascarbon tetrabromide and bromotrichloromethane. A catalytic chaintransfer agent such as a cobalt chelate complex could also be used, inwhich case it is possible that the hydrophilic oligomer (if used) inmixture A could itself be a macromonomer.

The amount of hydrophilic oligomer (if used) in mixture A is preferablywithin the range of from 0.2 to 20 weight % based on the total amount ofmonomer(s) employed in the invention polymerisation process, preferablyfrom 0.5 to 10 weight % and particularly from 1 to 5 weight %.

Surfactant(s) and hydrophilic oligomer(s) could be used in combinationin mixture A, in which case the maximum amounts used could beappropriately lowered from the preferred amounts of both mentioned abovealthough such preferred ranges as mentioned above could still be used.As mentioned above, combinations of different hydrophilic oligomers(e.g. acrylic and polyurethane hydrophilic oligomers) can also be used.

It will be apparent from the foregoing that in a particularly preferredvariant of embodiment G′ of the invention process there is provided aprocess for preparing a macromonomer using free radical-initiatedaqueous emulsion polymerisation in a polymerisation reactor of at leastone olefinically unsaturated monomer, which process employs ahydrophobic Co chelate catalyst(s) as a catalytic chain transferagent(s) for controlling molecular weight, a stabilising substance(s)for the emulsion polymerisation process, and a monomer feeding stage MFin which olefinically unsaturated monomer(s) to be polymerised is fed toa polymerisation reaction medium in the reactor and polymerised therein,

and wherein an aqueous pre-emulsified mixture A, comprising at leastpart of the Co chelate employed in the process, at least part of thestabilising substance(s) employed in the process, and part of themonomer(s) to be polymerised which is in at least partially polymerisedform, is prepared in or added to the reactor prior to the commencementof the monomer feed stage MF.

In the above variant of embodiment G′, the aqueous emulsion of mixture Amay be made up in the polymerisation reactor or may be preparedseparately and added thereto (this is intended to include the case wheresome of mixture A is prepared in the reactor and the rest of mixture Ais prepared outside the reactor and added thereto). The initiallydispersed monomer(s) dissolves the Co chelate(s), the polymerisation ofthis monomer(s) is initiated, and then after a reasonably short periodof time (e.g. preferably ≦60 minutes, more preferably ≦30 minutes andmost preferably 2 to 15 minutes) the monomer(s) of monomer feed stage MFis fed to the polymerisation reactor and its polymerisation thereincommenced (during this feeding period the monomer(s) of mixture A may ormay not have finished polymerising).

The monomer(s) fed to the reactor in feed stage MF of the inventionprocess may be fed over a significant period of time, e.g. over about 20to 480 minutes, more preferably over about 30 to 360 minutes and mostpreferably over about 120 to 255 minutes. It would also be possible tofeed it very quickly (all in one go) to the polymerisation medium in thereactor, so that the polymerisation would then effectively be a batchpolymerisation. Other polymerisation methods that are suitable for thispurpose include sequential or power feed polymerisation (the latter typeof polymerisation being described in U.S. Pat. No. 3,804,881 and U.S.Pat. No. 4,195,167). In these cases it will be appreciated that two ormore different feeds are employed which preferably differ in monomercomposition. The difference may be such as to introduce differentproperties in the different oligomer phases, including different Tg's,different functional monomers, different concentrations of functionalmonomers, and combinations of these.

The free radical yielding initiator may be any one (or more) of thoseknown to be useful for the aqueous emulsion polymerisation ofolefinically unsaturated monomers. Suitable examples include organicperoxides such as K, Na or ammonium persulphate, hydrogen peroxide, orpercarbonates, organic peroxides such as acyl peroxides including e.g.benzoyl peroxide or lauroyl peroxide, alkyl hydroperoxides such ast-butyl hydroperoxide and cumene hydroperoxide; dialkyl peroxides suchas di-t-butyl peroxide; peroxy esters such as t-butyl perbenzoate andthe like; mixtures may also be used, The peroxy compounds are in somecases advantageously used in combination with suitable reducing agents(redox systems) such as Na or K pyrosulphite or bisulphite, andiso-ascorbic acid. Metal compounds such as Fe.EDTA (EDTA is ethylenediamine tetracetic acid) may also be usefully employed as part of theredox initiator system. Azo functional initiators may also be used,examples of which include azobis(isobutyronitrile) and4,4′-azobis(4-cyanovaleric acid). Preferred initiators include ammoniumpersulphate, sodium persulphate, potassium persulphate,azobis(isobutyronitrile) and 4,4′-azobis(4-cyanovaleric acid). Mostpreferred are Na, K, and ammonium persulphates.

The initiator may be included entirely or substantially entirely withmixture A (or added thereto). It may also be separately added to thereactor to initiate polymerisation of the fed monomer(s) of feed stageMF. It may also be partly in mixture A and partly separately added tothe polymerisation reactor. However it is preferred to feed most if notall the initiator used to the polymerisation medium in the reactor(combined with and/or separately from the monomer(s) of feed stage MF).The initiator if added to the polymerisation medium in the reactor ispreferably fed as separate feed to the monomer(s) of feed stage MF sothat its feed time may be varied opposite the time of the monomer(s)feed (shorter or longer as well as the same).

The amount of initiator (or initiator system in cases where more thanone initiator component is used, as in e.g. redox systems) is preferablywithin the range of from 0.05 to 5 weight %, based on the total weightof monomer(s) used in the invention process, more preferably from 0.1 to3 weight %, and particularly from 0.3 to 1.5 weight % (typically 0.5 to0.75 weight %).

The polymerisation medium in the reactor is usually heated to effectfree radical-initiated polymerisation, with temperatures within therange of 30 to 100° C. being typical for many free radical initiators(more usually 30 to 90° C.). A further amount of initiator mayoptionally be added at the end of polymerisation to assist the removalof residual monomer(s).

Examples of olefinically unsaturated monomers which may be used to formthe macromonomers (some of which have already been mentioned above)include olefinically polyunsaturated monomers such as 1,3-butadieneisoprene; polyalkylene glycol di(meth)acrylates such as1,3-butyleneglycol diacrylate, ethylene glycol diacrylate; divinylbenzene; monolefinically unsaturated monomers include styrenes such asstyrene itself; α-methyl styrene and t-butyl styrene; meth(acrylic)amides and (meth)acrylonitrile; vinyl halides such as vinyl chloride;vinylidine halides such as vinylidene chloride; fluoro-containing vinylmonomers such as trifluoro ethyl methacrylates; vinyl ethers; vinylesters such as vinyl acetate, vinyl propionate, vinyl laurate and vinylesters of versatic acid such as VeoVa 9 and VeoVa 10 (VeoVa is atrademark of Resolution); heterocyclic olefinically unsaturatedcompounds; olefinically unsaturated acids such as acrylic acid,methacrylic acid, β-carboxyethyl acrylate and citraconic acid; alkylesters of mono-olefinically unsaturated dicarboxylic acids such asdi-n-butyl maleate and di-n-butyl fumarate and, in particular, esters ofacrylic acid and methacrylic acid of formula CH₂=CR¹-COOR² wherein R¹ isH or methyl and R² is optionally substituted alkyl of 1 to 20 carbonatoms (more preferably 1 to 8 carbon atoms) or cycloalkyl of 5 to 20carbon atoms (more preferably 5 to 8 carbon atoms) examples of which aremethyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate (allisomers), octyl (meth)acrylate (all isomers but particularly2-ethylhexyl (meth)acrylate), isopropyl (meth)acrylate, n-propyl(meth)acrylate, and hydroxyalkyl (meth)acrylates such as hydroxyethyl(meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl(meth)acrylate and their modified analogues like Tone M-100 (Tone is atrademark of Union Carbide Corporation). Such monomers of formulaCH₂=CR¹-COOR² when R¹=H are usually known as acrylate monomers and whenR¹=methyl are usually known as methacrylate monomers. The correspondingmacromonomers containing at least 40 weight % of such polymerisedmonomer units are herein called acrylic macromonomers (i.e. whetherderived from acrylate or methacrylate monomers or both).

In order to obtain a macromonomer, i.e. an oligomer having a highproportion of terminal unsaturation in its polymer chains (preferably atleast 80% of the chain having terminal unsaturation, more preferably atleast 90%), it is preferable to employ at least 20 weight % of at leastone (co)polymerisable α-methyl vinyl monomer for the monomer(s) used tomake the macromonomer, more preferably at least 50 weight % andparticularly at least 80 weight % (based on total monomer weight usedfor the polymerisation).

By a (co)polymerisable α-methyl vinyl monomer is meant herein a monomerof formulaCH₂=C(CH₃)−-Q   IIwhere Q is the residue of the monomer molecule and is preferablyselected from one or more of: a carbon acid group of formula C(=O)OR³ ora carbon amide group of formula C(=O)ONHR³ where R³ is H, optionallysubstituted C₁₋₁₈ alkyl, optionally substituted aryl (more preferablyphenyl and methyl substituted phenyl) and optionally substitutedalkaryl; CN; and optionally substituted aryl (more preferably phenyl ormethyl substituted phenyl).

Suitable α-methyl vinyl monomers (some of which have already beenmentioned above) include, for example, methacrylic acid, methacrylateesters, such as C₁ to C₁₈ normal or branched alkyl esters of methacrylicacid, including methyl methacrylate, ethyl methacrylate, n-butylmethacrylate, isopropyl methacrylate, cyclohexyl methacrylate,2-ethylhexyl methacrylate (all isomers), isobornyl methacrylate, laurylmethacrylate and stearyl methacrylate; hydroxyalkyl methacrylates suchas hydroxethyl methacrylate; glycidylmethacrylate; phenyl methacrylate;methacrylamide; methacrylonitrile; triethyl fluoro methacrylate; alphamethyl styrene; polyethyleneglycol(PEG) methacrylates;methoxypolyethylenglycol(MPEG) methacrylates, or combinations thereof.

Preferably the monomers used to form the macromonomer include anolefinically unsaturated acid monomer(s) preferably in an amount withinthe range of from 5 to 20 weight %, more preferably from 5 to 12 weight% based on the total amount of monomers used.

The ethylenically unsaturated monomers used to make the macromonomersmay also include, if desired, monomers carrying functional groups suchas crosslinker groups and/or hydrophilic water dispersing groups (asdiscussed above in respect of the oligomeric stabilising substance(s)which may be used in the invention process). Such functionality may beintroduced directly in the macromonomer by free radical polymerisation,or alternatively the functional group may be introduced by a reaction ofa reactive monomer which is subsequently reacted with a reactivecompound carrying the desired functional group. Some functional groupsmay perform more than one function, for example (meth)acrylic acid isusually used as a water-dispersing monomer however it may also act as acrosslinking monomer. Such variations are known to those skilled in theart.

Water-dispersing groups and water-dispersing monomers have beendiscussed above in respect of an oligomeric stabilising substance andsimilar considerations apply here with the proviso that it is not ofcourse necessarily required to use any ionic dispersing monomer(s) indissociated form, or indeed to use (if used at all) a sufficient amountof any dispersing monomer, to achieve the property ofself-dispersibility (very small amounts could be used, or indeed nonecould be used).

Examples of suitable water-dispersing groups and water-dispersingmonomers have been mentioned above in respect of the stabilisingsubstance when it is an oligomer and these groups could also be used inthe formation of the macromonomer, with acrylic acid and methacrylicacid being usually preferred in practice as the water-dispersingmonomers (if used at all of course).

The macromonomer formed in the invention process may, if desired,possess functional groups for imparting latent crosslinkability to anaqueous composition containing or derived from the macromonomer (latentcrosslinkability means that crosslinking takes place during and/or afterthe aqueous composition is subsequently dried) either when combined withan added crosslinking agent or by reaction with coreactant groups alsopresent in the macromonomer or other added polymer or by application ofsuitable radiation (combinations of two or more such techniques couldalso be used). The macromonomer could e.g. be combined with acrosslinking agent after its preparation said crosslinking agent beingreactable with crosslinkable groups also present in macromonomermolecules (or from other polymers of the composition) during and/orafter drying of the composition to effect crosslinking. For example, themacromonomer could carry groups such as hydroxyl groups and thecomposition subsequently formulated with a crosslinking agent such as apolyisocyanate, melamine, or glycoluril; or the functional groups on themacromonomer could include keto, aldeyde and/or acetoacetoxy carbonylgroups and the subsequently formulated crosslinker could be a polyamineor polyhydrazide such as adipic acid dihydrazide, oxalic aciddihydrazide, phthalic acid dihydrazide, terephthalic acid dihydrazide,isophorone diamine, 4,7-dioxadecane-1,10-diamine, or Jeffamine-T-403; ora crosslinker carrying semi-carbazide or hydrazide functional groups.Silane functional crosslinking agents such as the aminoalkyl silaneSilquest A-1110 (Witco) could also be used. Alternatively themacromonomer could contain hydrazide functional groups and thesubsequently formulated crosslinker could contain keto functionalgroups. The functional groups could include silane functional groups orhydroxyl functional groups reactive with silane groups, and thesubsequently formulated crosslinker could also comprise silanefunctional groups. The functional groups could also be unsaturateddouble bonds which undergo polymerisation to cause crosslinking on theapplication of suitable radiation (e.g. u.v. radiation).

Suitable monomers carrying crosslinker groups include for example allyl,glycidyl or hydroxyalkyl (meth)acrylates, acetoacetoxy esters,acetoacetoxy amides, keto and aldehyde functional vinyl monomers,keto-containing amides such as diacetone acrylamide, methylol and silanefunctional (meth)acrylic monomers.

Preferred crosslinking mechanisms (if used) include silane functionalgroup crosslinking and keto functional group with hydrazide functionalgroup crosslinking.

The resulting macromonomer may optionally comprise functional monomersthat act as adhesion promoters, such as Sipomer WAM (Rhodia), Cylink C4(Cytec), and Norsocryl 104 (Atofina), or monomers with long alkylchains, such as lauryl (meth)acrylate and stearyl (meth)acrylate oradhesion promoters such as β-naphthyl methacrylate (some of these havealready been mentioned above).

Preferably the weight average molecular weight of the macromonomer is inthe range of from 2,000 to 100,000 Dalton, more preferably 5,000 to50,000 Dalton and most preferably 8,000 to 35,000 Dalton.

The hydrophobic cobalt chelate complex used in the invention process ispreferably a cobalt II chelate having the following formula III:

wherein each group X, independently in each ring and in different rings,is a substituent selected from any alkyl but preferably of 1 to 14carbon atoms or cycloalkyl of 6 to 14 carbon atoms and any aryl butpreferably of 6 to 14 carbon atoms;n, independently in each ring, is 0 to 5;Z, independently on each boron atom, is selected from F, Cl, Br, OH,alkoxy of 1 to 12 carbon atoms, aryloxy of 6 to 12 carbon atoms, alkylof 1 to 12 carbon atoms and aryl of 6 to 12 carbon atoms;or two Z groups taken together provide on one or both boron atoms agroup —O—(T)—O—where T is a divalent aryl or alicyclic linking group oran alkylene linking group;or two Z groups taken together on one or both boron atoms provide a1,5-cycloctanediyl linking group;or being a cobalt III analogue of said cobalt II chelate of formula IIIin which the cobalt atom is additionally covalently bonded, in adirection at right angles to the macrocyclic chelate ring system, to H,halide or other anion, or a homolytically dissociable organic group;and wherein at least one further ligand may or may not be coordinated tothe cobalt II or cobalt III atom, being a ligand(s) which does not alterthe cobalt valency state.

The hydrophobic cobalt chelate may also be a Co II chelate having thefollowing formula IV:

where V is any alkyl group of ≧4 carbon atoms.

Referring now to Formula III, preferably X is alkyl of 1 to 14 carbonatoms, and may be straight-chained or branched if the option arises.More preferably X is alkyl of 1 to 4 carbon atoms and particularly ismethyl.

It is possible for n (representing the number of substituents in a ring)to be 0 in all rings (i.e. all the rings are unsubstituted so that eachring is phenyl). Preferably, n is 1 to 5 in at least two rings and morepreferably n is 1 to 5 in at least three rings and in particular n is 1to 5 in all four rings.

Preferably n is 1 to 3 in a substituted ring, more preferably n being 1or 2.

Preferably, when n is 1 to 3 in a substituted ring it has the same valuein each ring (if more than one ring is substituted), and more preferablyn is 1 or 2, and particularly n is 1 in each substituted ring.

When n=2, the substituents are preferably in the 3, 4 or 2, 4 positions.

When n=1, the substituent may be in the 2, 3 or 4 positions of a ring,preferably being at the same position in all substituted rings. It isparticularly preferred that the substituent is at the 2, 3 or 4 positionof all four rings, and especially at the 4 position of all four rings.

The groups Z are preferably all the same (or when taken together to forma divalent group such groups are the same on both boron atoms) and morepreferably are all F.

When both Z groups together provide a group —O—(T)—O— where T is adivalent aryl or alicyclic linking group, the group T preferably has 6to 10 carbon atoms and in such cases linkage is from adjacent ringcarbon atoms; more preferably T is o-phenylene or 1,2-cyclohexanediyl.

It is more preferred that the Co chelate of Formula III has thefollowing specific Formula V corresponding to Co II (bis4,4′-dimethylbenzildioxime diborondifluoride):

Specific examples of such hydrophobic Co chelate complexes of FormulaIII where X is alkyl are disclosed in U.S. Pat. No. 5,962,609 referenceto which is incorporated herein.

The macromonomers made using the invention process are useful in avariety of applications where they may be used as such, or polymerisedwith further olefinically unsaturated monomer(s) to form graftcopolymers, resulting e.g. in a comb-like chain morphology. Such furthermonomer(s) could usefully be or include e.g. (meth)acrylic monomer(s)and might e.g. comprise≧40 weight % of the further monomers polymerised,more preferably≧60 weight %. Such graft copolymers could usefully beprepared as an extension of the process to form the macromonomer, i.e.the further monomer(s) polymerised being second stage monomers, with thefurther polymerisation being carried out in the same or a differentreactor.

The macromonomers, or graft polymers derived therefrom, are particularlysuitable for use in coatings applications in which they may provide akey part of the coating compositions or formulations. Such coatingcompositions which can be pigmented or unpigmented will usually bewaterborne coating compositions since the macromonomer thereof has beenderived from aqueous emulsion polymerisation.

The coating compositions may be used for coating a variety of substratessuch as metals, wood, paper, board, leather, textiles, cementitiousmaterials, polymeric films or other plastics articles.

A further coating use for the macromonomers by the invention process, orgraft copolymers derived therefrom, is in graphics arts applications,wherein they may provide important components of water-based inks andoverprint varnishes.

Yet a further use for the macromonomers made by the invention process isin adhesives applications, wherein they, or products derived from them,may be employed in pressure sensitive, hot melt, contact and laminatingadhesives compositions. Such adhesives compositions may be water-basedor of the hot-melt-type.

The present invention is now illustrated but in no way limited byreference to the following examples. Unless otherwise specified allparts, percentages and ratios are on a weight basis (and the amount inparts for any component refers to that based on the total of allcomponents being used, including liquids such as water, and not just onthe total of solids). The prefix C before an example number denotes thatit is comparative.

In the examples, the following abbreviations and terms are specified:

-   MMA methyl methacrylate-   BA n-butyl acrylate-   MAA methacrylic acid-   DAAM diacetone acrylamide-   HEMA hydroxyethyl methacrylate-   AAEM acetacetoxyethyl methacrylate-   MPEG-350 ω-methoxypolyethyleneglycol methacrylate of Mw=350-   Mn number average molecular weight-   Mw weight average molecular weight-   MM macromonomer-   SLS sodium lauryl sulphate (100%)-   CCTP catalytic chain transfer polymerisation-   GPC gel permeation chromatography-   CTA chain transfer agent-   Co 4-MePhBF Co II (bis 4,4′-dimethylbenzil dioxime    diborondifluoride) (Formula V in description)-   PS particle size-   n.d. notdone

Molecular weights were determined by GPC relative to polystyrenestandards.

Preparation of Hydrophilic Oligomers

Hydrophilic oligomers for use as a stabilising substance in theinvention process were prepared using the following procedure, theseoligomers being obtained from the monomer compositions shown in Table 1below.

In a round-bottomed flask equipped with a stirrer and reflux condenser,64.31 parts of water and 0.08 parts of surfactant (SLS) were mixed andheated to 85° C. 5 weight % of a pre-emulsified feed of 20.09 parts ofmonomers as shown in Table 1, 8.57 parts of water, 0.25 parts of SLS and0.48 parts in Examples 1 to 13 and 0.14 parts in Examples 14 to 19 ofCTA (3-mercaptopropionic acid) was added to the reactor phase at 60° C.0.02 parts of ammonium persulphate initiator dissolved in 1.19 parts ofwater was added to the reactor phase at 80° C. At reaction temperaturethe remaining monomer feed was added over a period of 60 minutes. Aninitiator feed of 0.04 parts of ammonium persulphate dissolved in 2.77parts of water was added over a period of 70 minutes. When the initiatorfeed had been completed the reaction mixture was kept at 85° C. for 20minutes. After 20 minutes the temperature was reduced to 80° C. The pHof the reactor phase was increased to 9 using a mixture of 2.2 partsaqueous NH₃ (15.5% weight/weight in water). After 20 minutes mixing at80° C. the emulsion was cooled to room temperature and filtered.Typically the final product had a pH of 8.0 and a solids content of 21%.The molecular weight data for the hydrophilic oligomers formed is givenin Table 1 below.

EXAMPLES 1 TO 19

Macromonomers of MMA were prepared according to the invention process inthese examples using a precharge of a solution of Co chelate in MMAwhich was emulsified in water using the hydrophilic oligomers (asaqueous dispersions) prepared as described above as the stabilisingsubstance and then partially polymerised to form mixture A (embodimentG′ of the invention process).

In a round-bottomed flask (the reactor) equipped with a stirrer andreflux condenser 0.75 parts of the hydrophilic oligomer (as aqueousdispersion) was mixed with 0.75 parts of a preformed solution of Co4-MePhBF (CTA) in MMA at room temperature. The amount of cobalt chelatein each example is shown in Table 1. After mixing for 1 hour at roomtemperature the emulsified mixture was diluted with 58 parts of waterand heated to 75° C. thereby forming a pre-emulsified mixture. At 75°C., 0.008 parts of ammonium persulphate (APS) initiator dissolved in 0.3parts of water were added to the reactor phase to start thepolymerisation in the pre-emulsified mixture in the reactor and thereactor phase was further heated to 85° C. The reactor phase was kept at85° C. for 10 minutes, thereby to form pre-emulsified mixture A,embodiment G′. At this point a monomer feed stage MF, being 29.25 partsof MMA, and a (separate) APS initiator feed, comprising 0.142 parts ofinitiator and 5.7 parts of water and optionally 0.03 parts of SLS at apH of 8.5, to the reactor were started. The monomer feed and (separate)initiator feed were added over a period of 240 minutes. Following theaddition of the monomer feed the monomer feed tank was rinsed with 5parts of water, the rinsings added to the reactor, and thepolymerisation mixture kept at 85° C. for 90 minutes. The emulsion wascooled to room temperature and filtered. The final macromonomer aqueousemulsion typically had a solids content of 30%, a pH of 8.5 and aviscosity of 10 mpa.s. The particle sizes of the macromonomers are shownin Table 1 below. TABLE 1 Mw (kD) Wt ppm* SLS in Ex. Monomer compositionfor hydrophilic Cobalt Mw MM initiator PS MM No hydrophilic oligomeroligomer chelate (kD) feed (nm) 1 MMA/BA/MAA/DAAM = 50/34/10/8 12 1021.5 no n.d. 2 MMA/MAA/HEMA = 82/8/10 11 10 34.1 yes 76 3 MMA/MAA/AAEM =82/8/10 10 10 31.3 yes 79 4 MMA/AAEM = 90/10 11 10 55.6 yes 336 5MMA/MAA/DAAM = 82/8/10 11 40 10.8 yes 94 6 MMA/MAA/DAAM = 84/6/10 11 4016.2 yes 70 7 MMA/MAA/HEMA = 82/8/10 11 40 9.2 no 61 8 MMA/MAA/HEMA =82/8/10 11 40 11 yes 78 9 MMA/MAA/AAEM = 82/8/10 10 40 6.9 no 80 10MMA/MAA/AAEM = 82/8/10 10 40 7.7 yes 73 11 MMA/MAA/MPEG-350 = 82/8/10 1140 11.5 no 69 12 MMA/MAA/MPEG-350 = 82/8/10 11 40 12.2 yes 67 13MMA/BA/MAA/DAAM = 41/41/8/10 10 10 24.1 yes 119 14 MMA/MAA/DAAM =82/8/10 33 10 54.3 no 154 15 MMA/MAA/DAAM = 84/6/10 27 10 51.8 no 128 16MMA/BA/MAA/DAAM = 41/41/8/10 28 10 43.8 no 48 17 MMA/MAA/HEMA = 82/8/1027 40 10.3 yes 43 18 MMA/MAA/AAEM = 82/8/10 28 40 23.3 yes 43 19MMA/MAA/MPEG-350 = 82/8/10 29 40 12.3 yes 70*based on total weight monomer used.

EXAMPLES 20 TO 24

Macromonomers of MMA were prepared according to the invention processusing a precharge of a solution of Co chelate in MMA which wasemulsified in water using SLS as the stabilising substance (instead ofhydrophilic oligomer as used in Examples 1 to 19 above) and thenpartially polymerised to form mixture A (embodiment G′ of the inventionprocess).

In a round-bottomed flask (the reactor) equipped with a stirrer andreflux condenser X parts of SLS (see Table 2) were mixed with 0.75 partsof a preformed solution of Co 4-MePhBF (CTA) in MMA at room temperature.The total amount of stock solution (MMA plus cobalt chelate) was 0.75parts in total; however the amount of Co chelate was so low that thiswas very nearly the same as 0.75 parts of MMA. After mixing for 1 hourat room temperature the precharge was diluted with 58 parts of water andheated to 75° C. At 75° C., 0.008 parts of ammonium persulphateinitiator dissolved in 0.3 part of water was added to the reactor phaseto start the polymerisation of the MMA in the precharge and the reactorphase was further heated to 85° C. The reactor phase was kept at 85° C.for 10 minutes, thereby to form mixture A (embodiment G′). At this pointthe monomer feed stage MF (29.25 parts of MMA) and a (separate) APSinitiator feed, comprising 0.142 parts of the initiator and 5.7 parts ofwater and optionally 0.03 parts of further SLS to the reactor wasstarted. The monomer feed and initiator feed were added over a period of240 minutes. Following the addition of the monomer feed the feed tankwas rinsed with 5 parts of water, the rinsings added to the reactor, andthe polymerisation mixture kept at 85° C. for 90 minutes. The emulsionformed was cooled to room temperature and filtered. The finalmacromonomer aqueous emulsion typically had a solids content of 30%, apH value of 3 and a viscosity of 10 mPa.s. The Mw and particle sizes ofthe macromonomers are shown in Table 2 below. TABLE 2 % SLS on Parts SLSWt ppm* Mw MM PS MM Ex. No. monomer* on total Cobalt chelate (kD) (nm)20 2.3% 0.69 50 35 22 21 2.0% 0.60 50 32 28 22 1.5% 0.45 50 43 22 231.0% 0.30 50 24 18 24 1.5% 0.45 25 25 17*based on total weight of monomer used.

EXAMPLES 25 AND 26

Macromonomers of MMA were prepared according to the invention processusing a precharge of a solution of Co chelate in MMA which wasemulsified in water using hydrophilic oligomers (and not polymerised) toform mixture A, embodiment G′.

In a round-bottomed flask (the reactor) equipped with a stirrer andreflux condenser 47.169 parts of the hydrophilic oligomer (as aqueousdispersion) was mixed with 14.151 parts of a preformed solution of Co4-MePhBF (CTA) in MMA at room temperature (effectively 14.15 parts ofMMA). The amount of cobalt chelate in each example is shown in Table 3.After mixing for 1 hour at room temperature the emulsified mixture wasdiluted with 1196.2 parts of water and heated to 85° C. At 85° C., themonomer feed stage MF, being 566.03 parts of MMA, and a (separate) APSinitiator feed, comprising 2.83 parts of initiator and 110.37 parts ofwater and optionally 9.434 parts of SLS at a pH of 8.5, to the reactorwere started. The monomer feed and (separate) initiator feed were addedover a period of 240 minutes. Following the addition of the monomer feedthe monomer feed tank was rinsed with 53.8 parts of water, the rinsingadded to the reactor, and the polymerisation mixture kept at 85° C. for90 minutes. The emulsion was cooled to room temperature and filtered.The final macromonomer aqueous emulsion typically had a solids contentof 30%, a pH of 8.5 and a viscosity of 10 mpa.s. The Mw and particlesizes of the macromonomers are shown in Table 3 below. TABLE 3 Wt ppm*SLS in Ex. Hydrophilic oligomer Cobalt Mw MM initiator PS MM No Monomercomposition Mw(kD) chelate (kD) feed (nm) 25 MMA/MAA/HEMA = 82/8/10 1110 39 yes 78 26 MMA/MAA/HEMA = 82/8/10 11 40 10 yes 80

EXAMPLES 27 AND 28

Macromonomers of MMA were prepared according to the invention processusing a precharge of a solution of Co chelate, stabilised using ahydrophilic oligomer or a surfactant and (i) a non-polymerisable organicsolvent to form mixture A (embodiment G).

In a round-bottomed flask (the reactor) equipped with a stirrer andreflux condenser 35.38 parts of the hydrophilic oligomer (as aqueousdispersion) or 21.428 parts of SLS (aqueous solution was mixed with10.61 parts of a preformed solution of Co 4-MePhBF (CTA) in toluene atroom temperature (effectively 10.61 parts of toluene). The amount ofcobalt chelate in each example is shown in Table 4. After mixing for 1hour at room temperature the emulsified mixture was diluted with 906.08parts of water and heated to 85° C. At 85° C., the monomer feed stage MF(424.52 parts of MMA) and a (separate) APS initiator feed, comprising2.12 parts of initiator and 82.77 parts of water and optionally 7.075parts of SLS at a pH of 8.5, to the reactor were started. The monomerfeed and (separate) initiator feed were added over a period of 240minutes. Following the addition of the monomer feed the monomer feedtank was rinsed with 40.35 parts of water, the rinsing added to thereactor, and the polymerisation mixture kept at 85° C. for 90 minutes.The emulsion was cooled to room temperature and filtered. The finalmacromonomer aqueous emulsion typically had a solids content of 30%, apH of 8.5 and a viscosity of 10 mpa.s. The Mw and the particle sizes ofthe macromonomers are shown in Table 4. TABLE 4 Wt ppm* SLS in Ex.Cobalt Mw MM initiator PS MM No Stabilising compound chelate (kD) feed(nm) 27 Oligomer MMA/MAA/ 10 52 yes 66 HEMA = 82/8/10 28 1.5% on monomerSLS 10 42 yes 40

COMPARATIVE EXAMPLE 29

This was a comparative example in which a macromonomer of MMA wasprepared using a monomer feed process not according to the invention,using a mixture A with weight ratio of MMA to SLS outside 10/1 to 1/10.

In a round bottomed flask equipped with a stirrer and reflux condenser59.36 parts of water and 0.18 parts of the initiator4,4′-azobis(4-cyanovaleric acid) were mixed and heated to 85° C. As soonas the polymerisation temperature was reached, 10% of a monomer feedcomprising 9.78 parts of water, 1.22 parts of SLS (30 wt %), 600 weightppm of Co 4-MePhBF (CTA) (based on total MMA used) and 24.44 parts ofMMA was added. This was allowed to react for 5 minutes before theremainder of the monomer feed was added over a period of 90 minutes.Following the addition of the monomer feed the feed tank was rinsed with5 parts of water, the rinsings added to the reactor, and thepolymerisation mixture kept at 80° C. for 30 minutes. The emulsion wascooled to room temperature and filtered. The resulting macromonomeraqueous emulsion had a solids content of 25%, a pH of 3.2 and aviscosity of 5 mPa.s. Mw of the macromonomer was 42 kD, i.e. higher thanthose of most of the above-exemplified macromonomers made by theinvention process, (in a few cases comparable to them) even though 12 to60 times as much Co chelate catalyst was used. The Mw and particle sizeis shown in Table 5 below.

COMPARATIVE EXAMPLE 30

This was a comparative example in which no mixture A was used.

In a round bottomed flask equipped with a stirrer and reflux condenser1181.9 parts of water and 7.28 parts of the initiator4,4′-azobis(4-cyanovaleric acid) were mixed and heated to 85° C. As soonas the polymerisation temperature was reached, the monomer feedcomprising 201.12 parts of water, 12.13 parts of SLS (30 wt %), 40weight ppm of Co 4-MePhBF (CTA) (based on total MMA used) and 485.25parts of MMA was added over a period of 90 minutes. Following theaddition of the monomer feed the feed tank was rinsed with 100 parts ofwater, the rinsing added to the reactor, and the polymerisation mixturekept at 85° C. for 30 minutes. The emulsion was cooled to roomtemperature and filtered. The resulting macromonomer aqueous emulsionhad a solids content of 25%, a pH of 3.2 and a viscosity of 10 mPa.s.The Mw and particle size is shown in Table 5 below.

COMPARATIVE EXAMPLES 31 AND 32

These are comparative examples where a mixture A with a weight ratio ofMMA to SLS outside 10/1 to 1/10 and with 10 or 40 weight ppm of CTA wasused.

In a round bottomed flask equipped with a stirrer and reflux condenser1181.9 parts of water and 7.28 parts of the initiator4,4′-azobis(4-cyanovaleric acid) were mixed and heated to 85° C. As soonas the polymerisation temperature was reached, 10% of the monomer feedcomprising 201.12 parts of water, 12.13 parts of sodium lauryl sulphate(30 wt-%), 10 or 40 weight ppm of Co 4-MePhBF (CTA) (based on total MMAused) and 485.25 parts of MMA was added. The reaction mixture was keptfor 5 minutes at 85° C. Then the remaining monomer feed was added to thereaction mixture over a period of 90 minutes. Following the addition ofthe monomer feed the feed tank was rinsed with 100 parts of water, therinsings added to the reactor, and the polymerisation mixture kept at85° C. for 30 minutes. The emulsion was cooled to room temperature andfiltered. The resulting macromonomer aqueous emulsion had a solidscontent of 25%, a pH of 3.2, and a viscosity of 10 mPa.s. The Mw andparticle size is shown in Table 5 below. TABLE 5 Wt ppm * Mw C. Ex.Cobalt MM PS MM No Adjustments chelate (kD) (nm) 29 Ratio of MMA to SLSin A outside 600 42 150 10/1 to 1/10 30 No mixture A 40 76 120 31 Ratioof MMA to SLS in A outside 10 96 128 10/1 to 1/10 32 Ratio of MMA to SLSin A outside 40 75 140 10/1 to 1/10

1. Process for preparing a macromonomer using free radical-initiatedaqueous emulsion polymerisation in a polymerisation reactor of at leastone olefinically unsaturated monomer, which process employs ahydrophobic Co chelate catalyst(s) as a catalytic chain transferagent(s) for controlling molecular weight, a stabilising substance(s)for the emulsion polymerisation process, and a monomer feed stage MF inwhich olefinically unsaturated monomer(s) to be polymerised is fed to apolymerisation reaction medium in the reactor and polymerised therein;and wherein an aqueous pre-emulsified mixture A, comprising at leastpart of the Co chelate(s) employed in the process, at least part of thestabilising substance(s) employed in the process, and (i) anon-polymerisable organic solvent(s) and/or (ii) a polymerisableolefinically unsaturated monomer(s) in unpolymerised or at leastpartially polymerised form, is contacted in the reactor with monomer(s)of feed stage MF at the beginning of and/or during the course of feedstage MF; and wherein in mixture A the weight ratio of (i)non-polymerisable organic solvent(s) and/or (ii) polymerisableolefinically unsaturated monomer(s) in unpolymerised or at leastpartially polymerised form to stabilising substance(s) is in the rangeof from 10/1 to 1/10.
 2. Process according to claim 1 wherein saidpre-emulsified mixture A comprises a non-polymerisable organicsolvent(s) (but not a polymerisable olefinically unsaturated monomer(s)in unpolymerised or at least partially polymerised form) (embodiment G).3. Process according to claim 1 wherein said pre-emulsified mixture Acomprises a polymerisable olefinically unsaturated monomer(s) inunpolymerised or at least partially polymerised form (but not anon-polymerisable organic solvent(s)) (embodiment G′).
 4. Processaccording to claim 1 wherein said pre-emulsified mixture A comprises anon-polymerisable organic solvent(s) and a polymerisable olefinicallyunsaturated monomer(s) in unpolymerised or at least partiallypolymerised form (combination of embodiments G and G′).
 5. Processaccording to claim 1 wherein the aqueous pre-emulsified mixture A,comprising at least part of the Co chelate(s) employed in the process,at least part of the stabilising substance(s) employed in the process,and (ii) a polymerisable olefinically unsaturated monomer(s) which is inat least partially polymerised form, is prepared in or added to thereactor prior to the commencement of the monomer feed stage MF. 6.Process according to claim 1 wherein said olefinically unsaturatedmonomer(s) in mixture A is selected from one or more of methylmethacrylate, ethyl methacrylate and n-butyl methacrylate.
 7. Processaccording to claim 1 wherein all of the aqueous pre-emulsified mixture Ais contacted in the reactor with monomer(s) of feed stage MF at thebeginning of the monomer feed stage.
 8. Process according to claim 1which employs ≦100 weight ppm of Co chelate(s) based on the total weightof monomer(s) used for the polymerisation.
 9. Process according to claim1 wherein the amount of Co chelate(s) employed in mixture A is from 10to 100 weight % based on the total weight of Co chelate employed in thepolymerisation.
 10. Process according to claim 1 wherein in mixture Athe amount of (i) non-polymerisable organic solvent(s) and/or (ii)polymerisable olefinically unsaturated monomer(s) in unpolymerised or atleast partially polymerised form before contact with monomer(s) of feedstage MF is within the range of 1 to 20 weight % based on totalmonomer(s) used for the polymerisation.
 11. Process according to claim 1wherein said polymerisation process results in a macromonomer aqueousemulsion of particle size, as measured with light scattering equipment,within the range of from 10 to 300 nm.
 12. Process according to claim 1wherein the stabilising substance(s) employed in mixture A is asurfactant and/or a hydrophilic oligomer.
 13. Process according to claim12 wherein said hydrophilic oligomer(s) is an acrylic oligomer(s) and/ora polyurethane oligomer(s).
 14. Process according to claim 1 whereinsaid olefinically unsaturated monomer(s) used to form the macromonomeris selected from one or more of olefinically polyunsaturated monomerssuch as 1,3-butadiene isoprene; polyalkylene glycol di(meth)acrylates;divinyl benzene; monolefinically unsaturated monomers such as styrenes;meth(acrylic) amides and (meth)acrylonitrile; vinyl halides; vinylidinehalides; fluoro-containing vinyl monomers; vinyl ethers; vinyl esters;heterocyclic olefinically unsaturated compounds; olefinicallyunsaturated acids; alkyl esters of mono-olefinically unsaturateddicarboxylic acids; monosubstituted alkyl esters of monoolefinicallyunsaturated dicarboxylic acids; esters of acrylic acid and methacrylicacid of formula CH₂=CR¹-COOR² wherein R¹ is H or methyl and R² isoptionally substituted alkyl of 1 to 20 carbon atoms or cycloalkyl of 5to 20 carbon atoms.
 15. Process according to claim 1 wherein saidolefinically unsaturated monomer(s) used to form the macromonomercomprises at least 20 weight % of at least one (co)polymerisableα-methyl vinyl monomer for the monomer(s) used to make the macromonomer,(based on total monomer weight used for the polymerisation), where saidα-methyl vinyl monomer(s) has the formulaCH₂=C(CH₃)−Q   II where Q is the residue of the monomer molecule and isselected from one or more of: a carbon acid group of formula C(=O)OR³ ora carbon amide group of formula C(=O)ONHR³ where R³ is H, optionallysubstituted C₁₋₁₈ alkyl, optionally substituted aryl and optionallysubstituted alkaryl; CN; and optionally substituted aryl.
 16. Processaccording to claim 15 wherein said α-methyl vinyl monomer(s) is selectedfrom methacrylic acid, C₁ to C₁₆ normal or branched alkyl esters ofmethacrylic acid; hydroxyalkyl methacrylates; glycidylmethacrylate;phenyl methacrylate; methacrylamide; methacrylonitrile; triethyl fluoromethacrylate; alpha methyl styrene; polyethylene glycol (PEG)methacrylates; methoxypolyethylenglycol (MPEG) methacrylates, orcombinations thereof.
 17. Process according to claims 15 wherein themaximum amount of Co catalyst in the mixture A when (co)polymerising anα-methyl vinyl monomer(s) of formulaCH₂=C(CH₃)−Q   II is governed by the following empirical relationship:Mw [Co-complex]/m ^(1/2)≦0.35 Dalton   I where Mw is the achieved weightaverage molecular weight of the macromonomer in Dalton; [Co-complex] isthe concentration of Co chelate catalyst(s) in mixture A in mol ppmbased on total monomer(s) used in the invention process; and m is theaverage number of carbon atoms of the alkyl, aryl or aralkylsubstituent(s) of the α-methyl vinyl monomer(s) (or the weight averagenumber of the number of carbon atoms of such substituents if using morethan one α-methyl vinyl monomer).
 18. Process according to claim 1wherein the macromonomer which is formed in the process is an acrylicmacromonomer.
 19. Process according to claim 1 wherein the monomer(s)used to form the macromonomer includes a functional monomer(s) carryinga crosslinker group(s).
 20. Process according to claim 1 wherein themonomers used to form the macromonomer include an olefinicallyunsaturated acid monomer(s) in an amount within the range of from 5 to20 weight % based on the total amount of monomers used.
 21. Processaccording to claim 1 wherein the hydrophobic Co chelate used has FormulaIII

wherein each group X, independently in each ring and in different rings,is a substituent selected from any alkyl and any aryl; n, independentlyin each ring, is 0 to 5; Z, independently on each boron atom, isselected from F, Cl, Br, OH, alkoxy of 1 to 12 carbon atoms, aryloxy of6 to 12 carbon atoms, alkyl of 1 to 12 carbon atoms, and aryl of 6 to 12carbon atoms; or two Z groups taken together provide on one or bothboron atoms a group —O—(T)—O— where T is a divalent aryl or alicycliclinking group or an alkylene linking group; or two Z groups takentogether on one or both boron atoms provide a 1,5-cycloctanediyl linkinggroup; or being a cobalt III analogue of said cobalt II chelate offormula III in which the cobalt atom is additionally covalently bonded,in a direction at right angles to the macrocyclic chelate ring system,to H, halide or other anion, or a homolytically dissociable organicgroup.
 22. Process according to claim 21 wherein said Co chelate usedhas Formula V:


23. Process according to claim 1 wherein Co chelate us ed has FormulaIV:

where V is any alkyl group of ≧4 carbon atoms.
 24. Process according toclaim 1 wherein mixture A comprises a polymerisable olefinicallyunsaturated monomer(s) in at least partially polymerised form, andpreferably in substantially fully polymerised form, which is stored andused at a later time in the invention process, preferably being storedfor at least 1 day before subsequent use in the invention process. 25.Macromonomer made using a process according to claim 1 wherein themacromonomer contains at least ≦100 weight parts per million of the CoChelate catalyst(s) based on the total weight of monomer(s) used for thepolymerisation.
 26. Macromonomer according to claim 25 which has aweight average molecular weight within the range of from 2,000 to100,000 Dalton.
 27. Graft copolymer made by polymerisation of amacromonomer, said macromonomer made by a process according to claim 1,with an olefinically unsaturated monomer(s) and wherein the macromonomercontains essentially ≦100 weight parts per million of the Co Chelatecatalyst(s) based on the total weight of monomer(s) used for thepolymerisation.
 28. Graft copolymer made by polymerisation of amacromonomer according to claim 24 with an olefinically unsaturatedmonomer(s) and wherein the macromonomer contains essentially ≦100 weightparts per million of the Co Chelate catalyst(s) based on the totalweight of monomer(s) used for the polymerisation.
 29. A coatingcomprising a macromonomer according to claim
 25. 30. A coating accordingto claim 29 which is at least one of a film coating and an overprintvarnish.
 31. An adhesive which comprises a coating according to claim29.